1. Field of the Invention
The present invention relates to a method and device for generating a watermark-image data.
2. Description of the Related Art
A watermark printed on the background of an image or the like has been used as a pattern for preventing unauthorized copying. Because of the usefulness of the watermark, there has been an increasing demand for a method of efficiently generating watermark-image data.
Japanese Patent Application Laid-open No. 2005-295519, for example, discloses a conventional image processing device that generates a plurality of types of watermark images including a falsification-examination image and an unauthorized-copy examination image, and that superposes the images to generate a superposed image.
The conventional image processing device, however, generates data on a superposed image on a page basis. Generation of such a page-basis watermark-image data, which is not suitable for data compression, imposes a heavy load on a central processing unit (CPU).